When I visited the Furnace Creek NPS contact station in June a couple of years ago, ranger Charlie Callaghan looked worried. "We just pulled a body off the salt playa of Badwater Basin a few weeks ago," he informed me. "He died doing what you're planning to do, more or less."
I was there to pick up my permit before attempting the Lowest-to-Highest Trail, a backcountry hiking route from Badwater to Mt Whitney. It was the first portion of the route - in his jurisdiction, as it were - that had Charlie most concerned - the long, hot, arduous cross-country trek across Badwater Basin and up to Telescope Peak. My strategy was to night hike that stretch over a 48 hr period in an attempt to avoid the merciless broiling pan that Death Valley by day becomes at that time of year. Despite possessing a desert hiking resume that should have staved off most of my doubts, I still had some, and ranger Charlie a good deal more for me yet.
"He had been attempting to hike from Badwater to Telescope and back in a day. Made it to the top, then died within sight of his vehicle on the return." That's not so surprising, the ranger went on to explain. In that kind of heat, (120F+) the margin of safety is extremely thin. One minute the heat may appear manageable, the next you're lightheaded, weak, and can't go on. And incapacitation away from help quickly brings heat stroke, then death.
I never did make it beyond the briny pool of Badwater later that night. My rental car's outside temperature gauge was still reading 114 degrees at 10pm, and the desert wind was like a blowtorch, exacerbating rather than relieving the dessicating heat. Instead I opted to drive up to the cool heights of Wildrose campground for the night, then climbed 11,000 foot Telescope Peak as an out-and-back day hike. I had a fair amount of company on the hike, too, and none of us appeared to be suffering too much, but rather enjoying what amounted to a great hike at the perfect time of year.
The "L2H" remains to be completed, a goal awaiting some free time in autumn one of these years. Summertime heroics in the low country of Death Valley, it turns out, is primarily for fools.